'Never mind' = non importa, pazienza, non preoccuparti, lascia perdere according to the Collins-Sansoni dictionary. 'Never you mind' (colloquial) is more negative - 'non e' affar tuo'...similar to 'mind your own business'

"Never mind " is an expression that could mean : - don't worry , it doesn;t matter .,as you said " not a problem". - I was wrong , i withdraw the statement , i pretend i never said it , " Never mind what i said before " . another way to say sorry for what one have said . - never mind something = without considering something . They are going on that trip , never mind that they have work not finished yet . - but it doesn't mean " don't bother me again " i don't think so ,you could say Never mind me = Don't worry about me and what i am doing for example .

Nevermind is actually one word, not two words. But often it is misspelled, so it is ok, people still know what you mean. Just like "Alright" is one word, not two. Anyway, Nevermind means "just forget about it", so if someone says it to you abruptly, yes, that means that they do not want to hear from you again. But usually, it is polite, and is another way of saying " no worries , mate" or "sweet as, mate. It depends on the tone of voice. But us kiwis would never be rude about it! Cheers, Alex.